Undercover at Hogwarts
by choco-taco619
Summary: Nico goes undercover at Hogwarts to protect Harry and destroy Horcruxes. Will he be able to convince people he's a wizard, or will his secret be uncovered? This is NOT a Yaio, or MalexMale!
1. The Quest

**A/N: The Titan War is over, and Nico is sent undercover to Hogwarts to help out with the Wizarding War. It's Harry's fifth year at Hogwarts (The Order of the Peonix) and Nico and Harry are both fifteen. Hermione/Ron, Harry/Ginny, and Nico is single.**

**Disclaimer: I don't own Percy Jackson and the Olympians or Harry Potter. Their respective owners are Rick Riorden and J. K. Rowling.**

"Talking" - talking in English

_Thinking -_ thinking

**"Talking"** - talking in Ancient Greek

**Third Peron POV**

"Nico, I have a quest for you."

Nico looked up from the midnight black sword he was polishing. "Yes, Dad?"

The Lord of the Underworld sighed. "It seems that long ago Hectate blessed a group of ordinary humans with the gift of magic. No, they are not Hectatae's children. She thought that mortals should have, as she called it, 'their time to shine.' The problem is, there is a Dark Wizard named Tom Marvolo Riddle, though he goes by Lord Voldemort. Tom has found a way to cheat death."

"Cheat death? Evade you and Thatnos? Impossible!" Nico interrupted.

Hades replied, "Difficult, but not impossible. Have you ever heard of a Horcrux?"

Nico thought a minute before replying, "No. What is it?"

Hades answered his favorite son, "A Horcrux is what a wizard calls a split piece of soul. To create one, you must do terrible things. When someone has made a Horcrux, they cannot die. They just find where ever they hid their Horcrux and use it to create a new body."

Nico made a face. "That's disgusting. So this Tom you've been telling me about made a Horcrux?"

"He didn't make _a _Horcrux. He made _seven _Horcruxes." Nico's eyes widened. Hades continued, "Only the one named Harry Potter can kill Tom, but Tom will just keep evading death unless his Horcruxes are destroyed. That's where you come in. I want you to pose as a Hogwarts - " Nico snorted at the name " - student and keep Harry safe while looking for and destroying Horcruxes. You're the only one that can find them without having to do a lot of research. I'm counting on you to complete this task, Nico."

Nico nodded. "I just have a few questions, Dad." Hades nodded. "How do I pose as a student if a can't do magic?"

Hades replied, "Hectate had agreed to grant you the gift of magic temperarily. Since you will be starting in your sixth year, she put the knowledge of the spells the other students have learned in your head."

Satisfied, Nico moved onto his next question. "How will I get my things needed for school?"

"I have provided you with everything you need. It's all in this trunk." Hades waved his hand and a raven black trunk appeared.

"Will my teachers know of my being a demigod?" Nico continued.

"None of your teachers will know, and niether will your Headmaster. None of the students should be informed of your secret, either. Also, you should hide your weapons, as they would be confiscated at the school."

Nico nodded. "Last question, how will I get to Hogwarts?"

"You will shadow travel to King's Cross station in London, England by no later than eleven o' clock, their time on September first. When you get there walk into the wall between stations nine and ten. Don't shadow travel. Just walk into it, and you will arive at Platform Nine and Three Quarters. Then hand the conductor your ticket and board the train."

It sounded simple enough, but walking through a wall was a bit wierd.

"I understand, Dad. I'll do my best."

"I'm counting, on you Nico," said the Lord of the Dead. "Oh, and one more thing. I understand that there are an abundace of ghosts at Hogwarts. I have allowed them to stay there for the time being, so don't send them down here."

Nico nodded, though hesitantly. He didn't like ghosts that just stuck around. They should just except the fact that they were dead and move on.

Hades smiled, a sight only Nico had ever really seen. "Good luck, Nico."

Nico nodded, then went back to polishing his midnight sword.


	2. The Hoqwarts Express

**Herminone POV**

I was standing at King Cross Station about to go through the wall to Platform Nine and Three Quarters when my shadow dissappeared. I mean, it just flitted away. Harry and Ron noticed as well.

We brought out our wands and watched all the shadows in the room flee to a corner. The shadows seemed to take the form of a person. Then I realized that a boy was emerging from the shadows. It was like the shadows had created him. As soon as the boy was solid, all the shadows in the room went back to their rightful owners.

Wands at the ready, we walked up to the boy. "How did you do that?" I demanded.

When he looked at me, I noticed he had black eyes. You could barely ditinguish the eye from the pupil. Now that I observed him, everything about him was dark. Dark hair, dark eyes, dark clothes. The only thing with color was an orange shirt with strange symbols on it and a beaded necklace he was wearing.

"You're wizards," he stated.

Harry, Ron and I shared a look. He had an American accent. What do Americans know about wizards?

"You didn't answer my question," I said.

He studied me a minute. "That," he said, "is on a need-to-know basis. And you definatally don't need to know."

Ron glared at him. "Are you a Death Eater?" Ron demanded.

The boy snorted. "Heh heh. Eat Death. I don't think he* would taste very good."

"He?" asked Harry, confused.

The boy stopped laughing, and looked like he was mentally cursing himself. _What is up with this guy?_ I thought. _First he just appears out of shadows, knows were wizards, and talks about death like it's a peson that he knows personally. Talk about a freak._

"Ah...it doesn't look very appetizing. It. Not he. It."

Ron and Harry shared a look. "What's your name?" asked Harry.

"Nico di Angelo."

"Where are you from?"

"New York."

"Why are you here?"

"I'm an exchange student from America. I heard, well, my father heard, Hogwarts the best school around, so he made me transfer."

Harry seemed to except that answer and lowered his wand, but Ron still looked suspicious. "How do we know you're not evil?" Ron demanded.

"You don't," said Nico. Harry raised his wand again. Nico turned and walked through the wall, taking him to Platfroms Nine and Three Quarters.

"Let's follow him," I suggested. "I want to make sure he doesn't get someone into trouble." Harry and Ron nodded their agreement, and we walked through the wall.

**Nico POV**

Stupid wizards, asking so many questions. I almost slipped talking about Death Eaters. Something about imagining someone eating Thatnos was just so...funny.

I'm glad I made up that back story in advance. Hopefully, those three won't do their research and realize that there's not a magical school in New York. Unless you count Camp Half-Blood. It's more like a school for demigods than a summer camp for mortals. How many mortals do you see climbing rock walls that have lava pouring down the side? Not many, that's for sure.

I took the very last compartment on the train. I was all alone, but I preffered it that way

I felt someone's aura approaching. It was those three wizards from before! What did they want? The compartment door slid open. "All the other compartments are full. Can we sit here?"

I srugged. "Whatever." As long as they didn't ask me anymore questions, I was fine.

Coming in, the readhead tripped and landed on my trunk, causing it to somehow open and a picture of me and Bianca fell out, along with the Mythomagic Hades action figure that she wanted me to have.

"Sorry," he said, picking up the picture to hand it back to me. "Who is that?" he asked.

My throat clamped up. "My sister, Bianca."

The only girl picked up the action figure. "What is that?" she asked, clearly confused.

I responded, my throat clamping up even more. "A Mythomagic action figure. It was the last thing Bianca gave to me before she..." I trailed off, not wanting to end the sentence.

"Before she what?" he asked.

"Died," I whispered.

The compartment was quiet. "I'm sorry, mate," said the boy with the black hair.

"I'ts not your fault. So don't be sorry."

The boy could be Pecy's brother, if he didn't have glasses or that lightning shaped scar on his forehead. _Wait a minute..._ Dad had told me Harry Potter had a lightning shaped scar on his forhead. So this was him. Not like I imagined him. They boy was thin as a stick.

"What?" Harry asked, noticing my staring at him.

"You look like my cousin," I told him.

"Really?" he asked.

I nodded. "Yeah, if you were a bit older, and didn't have glasses or that scar. You could be his twin."

Harry seemed surprised. "Not many people I know have black hair and green eyes like me," he admitted.

"I know. Percy was the only one I knew who did. Until today, that is." I smiled slightly. I'm normally not a sociable person, but these people were genuine. They seemed pretty cool, too, except maybe the girl. She seemed more like a know-it-all than anything else.

"So, what are your names?" I asked. Might as well know who I'm talking to.

The redhead spoke first. "I'm Ron Weasly, that's Hermione Granger. And this is...Harry Potter."

The three waited for a reaction that never came. "Don't you know who he is?" asked Hermione, bewildered.

"Yes. He's the Boy-Who-Lived."

Ron spoke up. "Why didn't you give a reaction when you heard his name, then?"

"Isn't it obvious? No one likes being reminded off the day people the they loved died. I know that better than anyone," I spoke softly.

Harry looked at me with understanding, Ron and Hermione with pity.

Before they could say anything else, we arrived.

he* - Thatnos is Death, so when he is talking about eating death, he's talking about eating Thatnos


	3. The Sorting

A/N: I realized that in the first chapter, I said Nico was going to be a sixth year. I changed my mind, so he is going to be a fifth year, the same as Harry.

Nico POV

"Firs' years! Firs' years over here!" a man was calling over the crowd.

I supposed I should go with the first years, seeing as this was my first year here. I turned toward the sound of the voice and my hand immediately flew to the dagger concealed in the sleeve of my Aviator's jacket. The man was to large to be human, but he couldn't be a giant., To small for that. A half-giant maybe? Nico didn't know much about half-giants. He knew they were larger than the average human and extremely rare. And, for whatever reason, they couldn't smell demigods. However, they were able to see through the mist.

I was snapped out of the thoughts when Ron waved his hand in front of my face. "You okay there, mate?" he asked in that British accent of his.

"Who's he?" I demanded, jerking my head towards the man I had dubbed a half-giant.

Ron followed my gaze until he saw who I was talking about. He grinned. "Oh, that's just Hagrid. He's a bit intimidating when you first meet him, but he's a great guy deep down. He's the Keeper of the Keys and the Care of Magical Creatures Professor. Though, the magical creatures he usually brings in are more monsters and beasts than anything…he's got a real soft spot for them."

Ron's explanation didn't make me any more wary of the half-giant. My schedule had been chosen for me, and I hoped I didn't get Hagrid's class. All the monsters would most likely be attacking me rather than letting me care for them. But, my father must have known there would be monsters here, so maybe they weren't the same kind of monsters? After all, the wizard's definition of 'monster' is probably extremely different than a demigod's.

So, I slowly walked toward him, my hand still on my hidden dagger. When he saw me, he gave a warm smile. "You must be Nico!" he bellowed. "You just come with the firs' years and then McGonagall will tell you what to do."

I studied him for a minute and decided he was telling the truth. After all, my sixth sense, as I liked to call it, wasn't acting up, and monsters wouldn't kill hundreds of mortals just to kill a single demigod. Even if it was a son of Hades.

I walked with the other first years as Hagrid led us to a lake. "No more 'an four to a boat!" he bellowed.

I paled. We had to go across a lake? That was Poseidon's territory! I couldn't do that. Maybe Poseidon would understand and let me cross? Ha, who was I kidding? I'd be drowning before you could say "Olympus."

Maybe I could bribe him? It was worth a shot. I quickly pulled out a Drachma, muttered a prayer in Ancient Greek, and tossed it in the lake. I quickly got in a boat with a couple kids who gave me odd looks. As the boats started rowing themselves, I prayed with all my heart for Poseidon to let me across. To my relief, about three mermen came to the surface and soluted me. The message was clear – you can cross now, but don't expect it again.

I sent a silent thank you to my Uncle. About that time, I heard surprised gasps and mutters of awe. I looked up to see what the commotion was about, but I wasn't impressed. There was a castle, almost gothic in style. Sure, it was nice and all, but it didn't touch Mount Olympus.

We exited our boats and were led to oversize double doors. There, Hagrid stopped and handed us over to a strict looking lady. After a few exchanged words, Hagrid left, and the woman turned toward us to introduce herself. "I'm Professor McGonagall. I'll be teaching you lot Transfiguration this year. But we have more important things to discuss at the moment. You're about to be Sorted into your Houses." She paused to let the exited whisperings die down before she continued. "There are four Houses – Gryffindor, Hufflepuff, Ravenclaw, and Slytherin. Your House will be your family for as long as you spend at Hogwarts. We have a competition that we do here every year. Each House can either gain or be deducted points. You can gain points by answering questions correctly, getting perfect scores on tests, things of the like. You lose points when you're out after hours, talk back to teachers fight in the hallways, and generally doing things you shouldn't be. The House with the most points at the end of the year is awarded the House Cup. Now, let's get you Sorted."

The double doors opened up, and we nervously walked into the giant mess hall. Well, the first years walked in nervously. I was analyzing my surroundings, looking for the quickest way to exit if I need to flee a battle.

The Sorting was generally boring. The talking hat sang a song, then was placed on a students head and yelled out one of the four Houses names. After that, the hat would be removed, a table would clap, and the first year would scurry over to that table to find a seat.

Soon, I was the only one left.

The Headmaster – what was his name? Dumbbell? Dumbledee? No…Dumbledore! That's it – stood up and addressed the hall. "This year, we have an exchange student from America. He is in his fifth year. Please make him feel welcome!"

McGonagall then called out, "Di Angelo, Nico!" I walked up to the stool where a sat down, and the hat was placed upon my head.

Hmm…what do we have here?

I almost jumped, but controlled my actions. Wouldn't want to make it look like a was surprised, even if I was. _What are you doing in my head?_ I demanded. _Well, how else do you suppose I Sort you? Anyway, let me see your memories to see where you belong._ My eyes widened. _Wait, don't look there! _The hat paid me no heed, diving straight into my memories of the war. Then I heard the screaming.

At first, I thought it was my memories I was hearing, but then I realized that the hat was screaming. _So much for not raising suspicion,_ I thought with a grimace. Finally, the hat pulled out of my memories and panted out, "Sl-Slytherin."

The hat was lifted off my head. There was no clapping, only shocked faces. I walked purposefully toward the Slytherin table, finding a seat away from most of the other students.

Dumbledore was the first to snap out of his shock. "Well…let the feast begin."


End file.
